Browsing by Subject "sedimentit"

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  • Huurtomaa, Satu (Helsingin yliopisto, 2019)
    The Baltic Sea is a vulnerable marine environment and susceptible to pollution. The situation is especially severe in the Gulf of Finland due to a large catchment area compared to the size of the Gulf. The north eastern Gulf of Finland has been described as one of the most contaminated areas of the entire Baltic Sea, with extensive pollution load via river Kymi in the past. Still today, the currents bring contaminants from the eastern part of the Gulf – the Neva estuary and the Bay of Viborg. The concentrations of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Hg, Pb, Bi and La were studied in the surface sediments and three GEMAX cores. The vertical distribution revealed the temporal change in the metal accumulation. The spike in the Cs concentration, indicating the Chernobyl disaster in 1986, enabled the estimation of the accumulation of studied elements over time. The horizontal distribution maps based on the concentrations in the surface sediments enabled the discovery of the sites with most intense metal accumulation. Correlation coefficients showed the effect of carbon and sediment grain size in the distribution of metals. The comparison of the metal concentrations to the natural background levels and the Canadian sediment quality guidelines (SQGs) enabled the estimation of the degree of contamination of the area. The metal concentrations have declined during the last decades in the north eastern Gulf of Finland, indicating lower contamination input towards present day. However, in the oxidized Ravijoki core, the decline was not that obvious, probably due to metal scavenging by Fe and Mn oxides and bioturbation. The regional metal distribution was strongly affected by the grain size and carbon – most metals showed high positive correlations with carbon and finer sediment fraction. Mn was an exception, showing negative correlations with both carbon and clay, probably due to the Mn reduction at sites with high organic matter accumulation. The regional distribution pattern suggested main Cd pollution arriving from the eastern part of the Gulf. The distribution of Hg, Mo, Cu and Zn also suggested a possible source in the east. High concentrations of Hg, Pb and Cu were discovered in the outlets of river Kymi. According to the Canadian SQGs, the sediments in the north-eastern Gulf of Finland were contaminated. The situation is especially severe in the case of Zn – the higher reference value PEL, above which adverse biological effects frequently occur, was exceeded even in the oxidized Ravijoki sediments. The highest concentrations of the elements with defined SQGs (Cd, Cr, Zn, Cu, Hg, Pb and As) exceeded the lower reference values in the surface sediments, indicating that all these metals could, at least locally, pose a severe threat to benthic species.
  • Västilä, Kaisa; Väisänen, Sari; Koskiaho, Jari; Lehtoranta, Virpi; Karttunen, Krister; Kuussaari, Mikko; Järvelä, Juha; Koikkalainen, Kauko (MDPI, 2021)
    Sustainability 13, 16
    Conventional dredging of ditches and streams to ensure agricultural drainage and flood mitigation can have severe environmental impacts. The aim of this paper is to investigate the potential benefits of an alternative, nature-based two-stage channel (TSC) design with floodplains excavated along the main channel. Through a literature survey, investigations at Finnish field sites and expert interviews, we assessed the performance, costs, and monetary environmental benefits of TSCs in comparison to conventional dredging, as well as the bottlenecks in their financing and governance. We found evidence supporting the expected longer-term functioning of drainage as well as larger plant and fish biodiversity in TSCs compared to conventional dredging. The TSC design likely improves water quality since the floodplains retain suspended sediment and phosphorus and remove nitrogen. In the investigated case, the additional value of phosphorus retention and conservation of protected species through the TSC design was 2.4 times higher than the total costs. We demonstrate how TSCs can be made eligible for the obligatory vegetated riparian buffer of the European Union agri-environmental subsidy scheme (CAP-AES) by optimising their spatial application with respect to other buffer measures, and recommend to publicly finance their additional costs compared to conventional dredging at priority sites. Further studies on biodiversity impacts and long-term performance of two-stage channels are required.
  • Peltola, Sanni (Helsingin yliopisto, 2019)
    In recent decades, ancient DNA recovered from old and degraded samples, such as bones and fossils, has presented novel prospects in the fields of genetics, archaeology and anthropology. In Finland, ancient DNA research is constrained by the poor preservation of bones: they are quickly degraded by acidic soils, limiting the age of DNA that can be recovered from physical remains. However, some soil components can bind DNA and thus protect the molecules from degradation. Ancient DNA from soils and sediments has previously been used to reconstruct paleoenvironments, to study ancient parasites and diet and to demonstrate the presence of a species at a given site, even when there are no visible fossils present. In this pilot study, I explored the potential of archaeological sediments as an alternative source of ancient human DNA. I collected sediment samples from five Finnish Neolithic Stone Age (6,000–4,000 years ago) settlement sites, located in woodland. In addition, I analysed a lakebed sample from a submerged Mesolithic (10,000–7,000 years ago) settlement site, and a soil sample from an Iron Age burial with bones present to compare DNA yields between the two materials. Soil samples were converted into Illumina sequencing libraries and enriched for human mtDNA. I analysed the sequencing data with a customised metagenomics-based bioinformatic analysis workflow. I also tested program performance with simulated data. The results suggested that human DNA preservation in Finnish archaeological sediments may be poor or very localised. I detected small amounts of human mtDNA in three Stone Age woodland settlement sites and a submerged Mesolithic settlement site. One Stone Age sample exhibited terminal damage patterns suggestive of DNA decay, but the time of deposition is difficult to estimate. Interestingly, no human DNA was recovered from the Iron Age burial soil, suggesting that body decomposition may not serve as a significant source of sedimentary ancient DNA. Additional complications may arise from the high inhibitor content of the soil and the abundance of microbial and other non-human DNA present in environmental samples. In the future, a more refined sampling approach, such as targeting microscopic bone fragments, could be a strategy worth trialling.
  • Turunen, Jarno; Muotka, Timo; Aroviita, Jukka (Springer Link, 2020)
    Hydrobiologia 847 2
    Forestry-related land use can cause increasing instream sedimentation, burying and eradicating stream bryophytes, with severe ecological consequences. However, there is limited understanding of the relative roles and overall importance of the two frequently co-occurring stressors, increased fine sediments and loss of bryophytes, to stream biodiversity and ecosystem functions. By using random forest modeling and partial dependence functions, we studied the relative importance of stream bryophytes and fine sediments to multiple biological endpoints (leaf-decaying fungi, diatom, bryophyte, and benthic macroinvertebrate communities; leaf decomposition) using field survey data from headwater streams. Stream bryophyte abundance and richness were negatively related to fine sediment cover, highlighting the detrimental effect of sedimentation on bryophytes. However, bryophyte abundance was consistently more important a determinant of variation in community composition than was fine sediment cover. Leaf decomposition was influenced by shredder abundance, water temperature and, to a lesser degree, stream size. Our results suggest that the loss of stream bryophytes due to increasing sedimentation, rather than fine sediments per se, seems to be the key factor affecting multiple biological responses. Enhancing the re-establishment of bryophyte stands could partly compensate for the negative impacts of sedimentation on bryophytes and, consequently, on several other components of boreal stream ecosystems.
  • Coppock, Rachel L.; Lindeque, Penelope K.; Cole, Matthew; Galloway, Tamara S.; Nakki, Pinja; Birgani, Hannah; Richards, Saskiya; Queirós, Ana M. (Elsevier, 2021)
    Journal of Hazardous Materials 415: 125583
    Microplastics are ubiquitous in the marine environment, however, the mechanisms governing their uptake by, and burial within, seabed habitats are poorly understood. In this study, microplastic burial and its impact on fauna-mediated sedimentary processes was quantified at three coastal sites, and the potential contribution of burrowing faunal communities to this process assessed via functional trait diversity analysis of field data. In addition, laboratory exposures were used to assess whether sediment-processing undertaken by the brittlestar Amphiura filiformis, a key species in the sampled area, could explain the burial of microplastic fibres. Field observations confirmed broad-scale burial of microplastics across the coastal seabed, consistent across sites and seasons, with microplastic sequestration linked to benthic-pelagic exchange pathways, driven by burrowing fauna. Brittlestars were observed to bury and line their burrow walls with microfibres during experiments, and their burial activity was also modified following exposure to nylon fibres, relative to controls. Collectively, these results indicate that biodiverse and functionally important seabed habitats act as microplastic sinks, with burrowing fauna contributing to this process via well-known benthic-pelagic pathways, the rates of which are modified by plastic exposure.
  • Bergström, Irina (Finnish Environment Institute, 2011)
    Monographs of the Boreal Environment Research 38
    The carbon dioxide (CO2) and methane (CH4) fluxes from aquatic sediments have recently received considerable interest because of the role of these gases in enhancing climate warming. CO2 is the main end product of aerobic respiration and CH4 is produced in large amounts under anaerobic conditions. Shallow, vegetated sediments are an important source of both gases. CH4 may be transported via rhizomes and aerenchymal tissues of aquatic plants from the sediment to the atmosphere, thus avoiding oxidation in the aerated sediment surface and water column. Temperature is known to be a key factor affecting benthic CO2 and CH4 flux rates, but the interplay between other factors that may affect the fluxes from sediments is still poorly known. In order to study the spatial and temporal variability of carbon gas fluxes in boreal aquatic sediments, the area-based CO2 production rates in lake and brackish water sediments and CH4 emissions in vegetated lake littorals were measured in this work. The effects of temperature, sediment quality, plant species, zoobenthos and seasonal variation on flux rates were also estimated. The range of CO2 production rates measured in the field was 0.1–12.0 mg C m–2 h–1 and that of CH4 emission rates 0–14.3 mg C m–2 h–1. When incubated at elevated temperatures (up to 30 °C) in the laboratory, the CO2 production rates increased up to 70 mg C m–2 h–1. Temperature explained 70–94% of the temporal variation in the CO2 production in lake sites and 51% in a brackish water site. In the lake mesocosm, temperature explained 50–90% of the variation of CH4 emission. By contrast, CH4 oxidation rate was not dependent on temperature. The CH4 fluxes through the plants of six emergent and floating-leaved plant species were studied in the field (temperature range 20.4–24.9 °C). Stands of the emergent macrophyte Phragmites australis emitted the largest amounts of CH4 (mean emission 13.9 ± 4.0 (SD) mg C m-2 h–1), the mean emission rate being correlated with mean net primary production (NPP) and mean solar radiation. In the stands of floating-leaved Nuphar lutea the mean CH4 efflux (0.5 ± 0.1 (SD) mg C m–2 h–1) was negatively correlated with mean fetch and positively with percentage cover of leaves on the water surface. On a regional level, stands of the emergents P. australis and Equisetum fluviatile emitted 32% more CH4 than natural open peatland during the growing season, although their areal coverage in the study region was only 41% of that of peatland area. Climate warming will presumably increase the carbon gas emission from vegetated littorals. The model-based estimated increase of CO2 production rate in June was 29% and for CH4 emissions as much as 65% for the time interval of 110 years from 1961–1990 to 2071–2100. The results indicate that carbon gas fluxes from aquatic sediments, especially from vegetated littorals, are significant at the landscape level. They are linked to temperature but also to several other interacting factors such as e.g. water and bottom quality and ecosystem composition. Detailed investigation of the overall links between the causes and effects is urgently needed in order to understand and predict the changes caused by warming climate.
  • Bhattacharjee, Joy; Marttila, Hannu; Launiainen, Samuli; Lepistö, Ahti; Kløve, Bjørn (Elsevier, 2021)
    Science of The Total Environment 779 (2021), 146419
    Maintaining and improving surface water quality requires knowledge of nutrient and sediment loads due to past and future land-use practices, but historical data on land cover and its changes are often lacking. In this study, we tested whether land-use-specific export coefficients can be used together with satellite images (Landsat) and/or regional land-use statistics to estimate riverine nutrient loads and concentrations of total nitrogen (TN), total phosphorus (TP), and suspended solids (SS). The study area, Simojoki (3160 km2) in northern Finland, has been intensively drained for peatland forestry since the 1960s. We used different approaches at multiple sub-catchment scales to simulate TN, TP, and SS export in the Simojoki catchment. The uncertainty in estimates based on specific export coefficients was quantified based on historical land-use changes (derived from Landsat data), and an uncertainty boundary was established for each land-use. The uncertainty boundary captured at least 60% of measured values of TN, TP, and SS loads or concentrations. However, the uncertainty in estimates compared with measured values ranged from 7% to 20% for TN, 0% to 18% for TP, and 13% to 43% for SS for different catchments. Some discrepancy between predicted and measured loads and concentrations was expected, as the method did not account for inter-annual variability in hydrological conditions or river processes. However, combining historical land-use change estimates with simple export coefficients can be a practical approach for evaluating the influence on water quality of historical land-use changes such as peatland drainage for forest establishment.
  • Albrecht, Horst; Carman, Rolf; Jensen, Arne; Jonsson, Per; Kankaanpää, Harri; Larsen, Birger; Leivuori, Mirja; Niemistö, Lauri; Uscinowicz, Szymon; Winterhalter, Boris (Merentutkimuslaitos, 2003)
    Meri 50
  • Wood, Steffaney M.; Kremp, Anke; Savela, Henna; Akter, Sultana; Vartti, Vesa-Pekka; Saarni, Saija; Suikkanen, Sanna (Frontiers in Microbiology, 2021)
    Frontiers in Microbiology 12
    Cyanobacteria of the order Nostocales, including Baltic Sea bloom-forming taxa Nodularia spumigena, Aphanizomenon flosaquae, and Dolichospermum spp., produce resting stages, known as akinetes, under unfavorable conditions. These akinetes can persist in the sediment and germinate if favorable conditions return, simultaneously representing past blooms and possibly contributing to future bloom formation. The present study characterized cyanobacterial akinete survival, germination, and potential cyanotoxin production in brackish water sediment archives from coastal and open Gulf of Finland in order to understand recent bloom expansion, akinete persistence, and cyanobacteria life cycles in the northern Baltic Sea. Results showed that cyanobacterial akinetes can persist in and germinate from Northern Baltic Sea sediment up to >40 and >400 years old, at coastal and open-sea locations, respectively. Akinete abundance and viability decreased with age and depth of vertical sediment layers. The detection of potential microcystin and nodularin production from akinetes was minimal and restricted to the surface sediment layers. Phylogenetic analysis of culturable cyanobacteria from the coastal sediment core indicated that most strains likely belonged to the benthic genus Anabaena. Potentially planktonic species of Dolichospermum could only be revived from the near-surface layers of the sediment, corresponding to an estimated age of 1–3 years. Results of germination experiments supported the notion that akinetes do not play an equally significant role in the life cycles of all bloom-forming cyanobacteria in the Baltic Sea. Overall, there was minimal congruence between akinete abundance, cyanotoxin concentration, and the presence of cyanotoxin biosynthetic genes in either sediment core. Further research is recommended to accurately detect and quantify akinetes and cyanotoxin genes from brackish water sediment samples in order to further describe species-specific benthic archives of cyanobacteria.
  • Lehtoranta, Jouni (Finnish Environment Institute, 2003)
    Monographs of the Boreal Environment Research 24
    One of the main threats facing the Baltic Sea is eutrophication due to an excess supply of nutrients. In the Gulf of Finland, primary productivity and biomasses of autotrophic and heterotrophic organisms are among the highest in the Baltic. The high biomasses are attributed mainly to the eutrophying effects of the large land-derived nutrient inflow from St. Petersburg and via the River Neva. The role of sediment phosphorus (P) in eutrophication is, however, poorly understood in the Gulf. The aim of this study was to obtain information on the regional levels of sediment P and to specify the pools of P. Efforts were also made to define the sediment retention ability of P along the estuarine gradient, to establish the factors that affect the benthic fl ux of P and to assess whether sulphur (S) is a significant factor in sediment P cycling. On the basis of the results it was possible to quantify and consider the ecological implications of the benthic flux of P.The sediments of the Gulf are rich in organic matter, nitrogen (N) and P. A large portion of the mobile pool of P in these sediments consists of iron (Fe)-bound P, which is released when Fe(III) oxides are reduced under anoxic conditions. The increase in the sediment organic matter concentration along the estuarine gradient seems to impair the sediments’ ability to retain P. The highest benthic P efflux was measured in summer and the lowest in winter. The decrease in the near-bottom oxygen concentration in summer may favour anaerobic sulphate reduction followed by iron sulphide (FeS) formation close to the sediment- water interface. In the sediment, the key role in preventing P from entering the water is played by the binding ability of P related to diffusing Fe. In the brackish Baltic Sea, in contrast to most lake systems, the diffusion of Fe may be inactivated by FeS formation. Thus, high effluxes of P to oxic water were measured on bottoms where black sediment indicating the presence of FeS extended to the surface of the sediment.The P released from the sediments of the Gulf itself may largely explain the high P concentrations and low N:P ratios in near-bottom waters in summer and, after autumn mixing, in the entire water column. However, the input of P from the main Baltic basin may also lead to an increase in P concentrations in the Gulf. The high release rates of P measured – rather than denitrification – largely explain the N limitation of the primary production. A relationship seems to exist between the increase in near-bottom salinity and the weakening of the sediment oxidation state of the Gulf since 1996. The inflow of saline water to the Gulf strengthens density stratification, thus favouring the release of P to water. Therefore, the variations in hydrological factors may produce a marked between-year variation in the benthic P efflux and counteract the reduction in the external P load. The ability of sediment to retain P could most likely be promoted by decreasing the sedimentation of labile organic matter on the bottom. Organic matter sedimentation could be lowered by cutting the amount of bioavailable N and P from an anthropogenic sources.
  • Salminen, Sarianna; Tammelin, Mira; Jilbert, Tom; Fukumoto, Yu; Saarni, Saija (Kluwer Academic, 2021)
    Journal of Paleolimnology 2021
    The influence of lake restoration efforts on lake bottom-water conditions and varve preservation is not well known. We studied varved sediments deposited during the last 80 years along a water-depth transect in the Enonsaari Deep, a deep-water area of the southernmost Enonselkä Basin, Lake Vesijärvi, southern Finland. For the last few decades, the Enonselkä Basin has been subject to ongoing restoration efforts. Varve, elemental, and diatom analyses were undertaken to explore how these actions and other human activities affected varve preservation in the Enonsaari Deep. In contrast to most varved Finnish lakes, whose water columns have a natural tendency to stratify, and possess varve records that span thousands of years, varve formation and preservation in Lake Vesijärvi was triggered by relatively recent anthropogenic stressors. The multi-core varve analysis revealed that sediment in the Enonsaari Deep was initially non-varved, but became fully varved in the late 1930s, a time of increasing anthropogenic influence on the lake. The largest spatial extent of varves occurred in the 1970s, which was followed by a period of less distinguishable varves, which coincided with diversion of sewage from the lake. Varve preservation weakened during subsequent decades and was terminated completely by lake aeration in the 2010s. Despite improvements in water quality, hypolimnetic oxygen depletion and varve preservation persisted beyond the reduction in sewage loading, initial aeration, and biomanipulation. These restoration efforts, however, along with other human actions such as harbor construction and dredging, did influence varve characteristics. Varves were also influenced by diatom responses to anthropogenic forcing, because diatoms form a substantial part of the varve structure. Of all the restoration efforts, a second episode of aeration seems to have had the single most dramatic impact on profundal conditions in the basin, resulting in replacement of a sediment accumulation zone by a transport or erosional zone in the Enonsaari Deep. We conclude that human activities in a lake and its catchment can alter lake hypolimnetic conditions, leading to shifts in lake bottom dynamics and changes in varve preservation.
  • Heikkilä, Raimo (Finnish Environment Institute, 1999)
    Monographs of the Boreal Environment Research 15
  • Björklöf, Katarina; Leivuori, Mirja; Lepistö, Jani; Vepsäläinen, Milja; Väisänen, Ritva (Suomen ympäristökeskus, 2016)
    Suomen ympäristökeskuksen raportteja 42/2016
    Vertailukokeessa yhdeksän kenttätoimijaa otti näytteet sedimenttikasasta metallien pitoisuuksien määrittämiseksi. Osallistujat suorittivat toisistaan riippumattomasti ja laatimiensa suunnitelmien mukaisesti näytteenoton. Vertailukokeen tulokset osoittavat, että alan kenttätoimijoilla on pääasiassa hyvä osaaminen. He toimivat sekä vastuullisesti että huolellisesti kentällä. Myös työsuojelusta oli huolehdittu hyvin. Osallistujat käyttivät useita toimivia näytteenottostrategioita ja –välineitä. Näytteenottajat toimivat laadittujen suunnitelmien mukaisesti kentällä ja kirjasivat tärkeimmät havaintonsa kenttälomakkeisiin. Vain kolme osallistujaa kahdeksasta esitti kalibrointitodistuksen XRF-laitteensa kalibroinnista. Näytteiden lukumäärän tai osanäytteiden lukumäärän vaikutuksesta tuloksen oikeellisuuteen ei saatu näyttöä. Testikohteessa suurin tulosten tulkintaan epävarmuutta aiheuttava tekijä oli kasan heterogeenisyys. Lämmin kiitos kaikille osallistujille!
  • Vuori, Kari-Matti; Swanljung, Tea; Aaltonen, Eeva-Kaarina; Kalliolinna, Marjo; Jokela, Sinikka (Suomen ympäristökeskus, 2009)
    Suomen ympäristö 1/2009
    Kokkolaan on keskittynyt Pohjoismaiden merkittävin metalli- ja kemian alan teollisuus. Kokkolan edustan merialuetta kuormittavat teollisuuden päästöt sekä Kokkolan kaupunki. Jätevedet sisältävät mm. raskasmetalleja sekä orgaanisia yhdisteitä. Myös Perhonjoen kautta huuhtoutuu merialueelle erityisesti ylivirtaamakausina metalleja, jotka ovat  seurausta valuma-alueen happamien sulfaattimaiden (HS-maat) kuivatuksista. Merialuetta on tarkkailtu yli 30 vuoden ajan. Teollisuuden metallipäästöt ovat tänä aikana pudonneet murto-osaan lähtötilanteesta. HS-maiden metallikuormien suhteellinen osuus on kasvanut. Eliöiden ja sedimenttien metallitasot ovat laskeneet, mutta ovat edelleen kohonneita. Pohjaeläinlajistossa on ollut viitteitä  toksisuudesta. Ympäristölainsäädäntö korostaa entistä painokkaammin tarvetta arvioida ihmisen toimista aiheutunutta ekologista haittaa. Tätä varten tulee selvittää missä määrin ekosysteemit ja niiden osat altistuvat haittatekijöille ja minkälaisia vaikutuksia altistumisesta seuraa. Tältä pohjalta voidaan arvioida riskien mittakaavaa ja merkitystä sekä suunnata ja kehittää tarkkailuohjelmia  ja ympäristönsuojelutoimenpiteitä. Osana Kokkolan edustan velvoitetarkkailuohjelmaa käynnistettiin ensimmäisen kerran vuonna 2005 ekotoksikologinen tutkimus ja ekologinen riskinarvio.   Tutkimuksessa tarkasteltiin Kokkolan edustan sedimenttien altistumista haitallisille aineille sekä niiden aiheuttamaa akuuttia ja kroonista toksisuutta. Kohteena olivat syvännepohjat, jotka käsittivät tehtaiden edustat ja ulommat kohteet  sekä Perhonjoen edustan (HS-maiden vaikutus).  Altistuksen indikaattorina olivat sedimenttien raskasmetallipitoisuudet, joita verrattiin saastuneiden maiden raja-arvoihin ja tavoitetasoihin. Akuutin toksisuuden testaukseen käytettiin valobakteeritestiä (SFS-EN ISO 11348). Kroonista toksisuutta arvioitiin surviaissääskien epämuodostumia hyödyntävällä tutkimuksella. Altistumis- ja vaikutusprofiilien yhteistarkastelun perustella laadittiin riskiarvio näyteasemittain. Uloimmassa kohteessa (n. 7 km päästölähteistä) riski oli alhainen, tehtaiden edustalla lievästi kohonnut – kohtalainen, Perhonjoen edustalla alhainen – kohtalainen. Riski oli korkea kohteessa mikä tulkittiin ruoppausmassojen vaikuttamaksi alueeksi. Tutkimus osoitti, että Kokkolan edustan merialueen sedimentissä haitallisten aineiden pitoisuudet ovat tasolla, joka aiheuttaa pohjaeläinyhteisölle paikoin merkittäviä toksisuushaittoja. Haittoja aiheuttavat sekä piste- että hajakuormitus. Haitta-aineita olivat mm. Hg, Cd, Zn ja As. Tämä tutkimus on tiettävästi ensimmäinen Suomessa tehty surviaissääskien epämuodostumista hyödyntävä tutkimus merialueelta. Määritysmenetelmä oli herkkä ja vaikutti soveltuvan myös velvoitetarkkailuna toteutettavaan haitallisten aineiden seurantaan  rannikkovesissä. Surviaissääskien keruu maastosta osoittautui kuitenkin työlääksi. Näytteistä saatujen yksilöiden pieni määrä ja epätasainen jakautuminen näyteasemien ja tutkittujen sukujen välille heikensivät tulosten luotettavuutta. Jatkossa sedimenttinäytteiden toksisuutta tulisi selvittää surviaissääskien morfologisiin häiriöihin perustuvina laboratoriotesteinä. Tällöin voidaan vakioida altistettavien eläinten määrä ja laji. Näin saadaan luotettavampi kuva toksisuushaittojen luonteesta, ajallisesta ja paikallisesta vaihtelusta ja haittojen kehityksestä. Tarkkailuja tulisi kehittää kokonainaisuutena, missä käyttö-, päästö- ja vaikutustarkkailu muodostavat ERA (Ekologinen riskianalyysi) -prosessia hyödyntävän kokonaisuuden. Painotusten tulisi vaihdella toisiaan tukien ja toksisuuden testauksen ja aineiden tunnistamisen edetä johdonmukaisesti.
  • Heikkinen, Janne (Helsingfors universitet, 2011)
    The ambition of the agricultural environmental programme is to reduce nutrient load, because greater part of the diffuse loading of phosphorus is caused by agriculture. A eutrophic influence of the phosphorus in water systems tends to be limited inter alia by constructed wetlands. Their main task is to allow sedimentation of eroded soil into the bottom of the wetlands. There is ambiguity on the findings of the functionality and the importance of the prevention of water loading among scientific research in Finland. The aim of this study is to examine by utilizing soil analyses what happens to the basin water eroded phosphorus in the wetland sediment and wether the sedimentary constituent of the soil be suitable for a substratum of plant production. Comparing the samples of basin soil and wetland sediments revealed that the eroded constituent of the basin soil got assorted on wetlands. The samples collected from the wetlands contained 48 % more clay than the samples collected from the basin soil. The growth of the clay concentration increased the reactive area of the sediment. In consequence, it contained 45 % more hydroxides of aluminium and iron in the samples of the sediment than the samples of the basin soil. Because of the hydroxides, the phosphorus sorption capacity was 52 % higher than in the samples of the basin soil. However, the degree of phosphorus saturation was equal in the sediment and basin soil, because the oxidized sediment contained 50 % more phosphorus extracted from hydroxides of aluminium and iron. At the time of sampling the sediment was in reduced state and the amount of its water extracable phosphorus was significantly higher compared to the oxidized sediment. Correspondingly, when the sediment became oxidized the sorption capacity for phosphorus increased significantly, therefore the phosphorus was desorbed from reduced sediment to the wetlands water. This was also proven in a pot experiment, where rye-grass that grew in the sediment suffered from a severe shortage of phosphorus. In contrast, rye-grass grown in the basin soil didn’t suffer from the deficiency of phosphorus at the same fertilization levels. After threefold extra fertilization of phosphorus, the dry matter yield, concentration of phosphorus and uptake of phosphorus on the second yield grown in sediment were equal to the results of the first yield grown in basin soil. According to the results of the pot experiment, the sediment in reduced state is weakly suitable for the substratum of plant production, because the sorption capacity of phosphorus is high. Instead, sediment suits well to be utilized in the areas wherein the soil includes plenty of easy soluble phosphorus, such as for the material of subgrade for the corral of livestock, because the sediment reduces the load of phosphorus directed to the environment.
  • Ruoppa, Marja; Mäkinen, Irma; Lappalainen, Juha; Jälkö, Leila (Suomen ympäristökeskus, 2007)
    Suomen ympäristökeskuksen raportteja 28/2007
  • Martinmäki, Kati; Ulvi, Teemu; Visuri, Mika (Suomen ympäristökeskus, 2012)
    Suomen ympäristökeskuksen raportteja 3/2013
    Oulussa tiiviin asutuksen keskellä sijaitseva Pyykösjärvi on rehevöitynyt, matala järvi, jossa on toistuvasti esiintynyt leväkukintoja kesällä ja happikatoja talvella jo 1970-luvulta lähtien. Pyykösjärven tilan heikkenemisestä johtuvat ilmiöt ovat vähentäneet sen virkistyskäyttömahdollisuuksia. Ongelmien vähentämiseksi järveä hapetettiin talvisin 25 vuoden ajan, mutta järven tila ei parantunut. Marraskuussa 2010 Oulun kaupunki aloitti lisäveden pumppaamisen Oulujoesta Pyykösjärveen ja hapetus lopetettiin. Vettä on pumpattu siitä lähtien talvisin marraskuun alun ja maaliskuun lopun välisenä aikana yhteensä neljän kuukauden ajan noin 0,1 m3/s. Matalan sisäkuormitteisen järven kunnostaminen – Pyykösjärven tapaustutkimus (PyyVesi) –hankkeen päätavoitteena oli arvioida Oulujoesta pumpattavan lisäveden vaikutuksia Pyykösjärven veden laatuun ja ekologiaan. Lisäksi tavoitteena oli tunnistaa matalan järven sisäisen kuormituksen syntymekanismeja ja testata eräiden mittausmenetelmien soveltuvuutta sisäisen kuormituksen arviointiin. Pyykösjärven fosforipitoisuudet ovat olleet vuosina 2011 ja 2012 selvästi alhaisempia kuin ennen lisävesien johtamista. Typpipitoisuudet ovat puolestaan vaihdelleet voimakkaasti. Lisävedet ovat laimentaneet järviveden pitoisuuksia. Järvi happamoitui äkillisesti toistaiseksi tuntemattomasta syystä kesällä 2010. Alhainen pH on todennäköisesti myös vaikuttanut ravinnepitoisuuksiin, mutta sen merkitystä pitoisuuksiin ei voitu arvioida. Lisävesien johtamisella ei ole kuitenkaan voinut olla vaikutusta Pyykösjärven happamoitumiseen. Talviaikaiset happipitoisuudet ovat pysyneet Pyykösjärvessä riittävän suurina kahtena ensimmäisenä talvena, jolloin lisävettä on pumpattu järveen. Vaikka hapenkulutus järvessä on voimakasta talvella jääkannen alla ja pitoisuudet alenevat voimakkaasti, ovat happipitoisuudet olleet alimmillaankin 1–2 mg/l joka puolella järveä. Lisävesien mukana tulee Pyykösjärveen yli kolminkertainen määrä happea verrattuna aiemman ilmastimen hapetustehoon. Mallinnustulokset osoittavat, että lisävedet sekoittuvat tehokkaasti kaikkialle järvessä. Parantuneen happitilanteen takia myös sisäinen kuormitus on todennäköisesti vähentynyt. On odotettavissa, että järven tila tulee hitaasti paranemaan lisävesien johtamisen myötä.
  • Alhonen, Pentti; Miettinen, Veijo; Häsänen, Erkki (Vesihallitus, 1973)
    Vesientutkimuslaitoksen julkaisuja 7
    Seloste: Pohjan elohopeapitoisuus eräillä likaantuneilla vesialueilla
  • Verta, Matti; Kauppila, Tommi; Londesborough, Susan; Mannio, Jaakko; Porvari, Petri; Rask, Martti; Vuori, Kari-Matti; Vuorinen, Pekka J. (Suomen ympäristökeskus, 2010)
    Suomen ympäristökeskuksen raportteja 12/2010